Many industries require the mixing of fluids of different types and colors to provide desired formulations. The mixing of custom paint colors, inks for printing, and various dyes for dyeing and printing textiles are examples of such industries.
In the printing of cloth a large variety of different colors is required. These colors have been formulated in the past by the use of technicians who measure various amounts of the different materials including colored materials for tinting. Many of these materials can produce great changes in the color texture with small variations in volume. A typical formulation might include 15 different components varying in total amount from a few ounces to several gallons for one formulation. Moreover, it is often required in a large mill to use a new formulation every few minutes.
Present methods for producing formulations include using various hand-measuring containers. The components are measured into various containers and then added to a single drum where they are later agitated and transported to the machine on which they are to be used. Apart from requiring considerable manpower, there are many drawbacks to this hand method because of human error. An operator may forget the exact measurements he has made, he may not be accurate within the time limitations required, and unclean containers may contaminate mixtures.
Attempts have been made to improve hand methods by utilizing standard paint pumps to pump individual components into a single drum for mixing. In such systems the amounts of the individual components dispensed are controlled by limit switches on the individual pumps so that the number of pump strokes can be counted thereby controlling the volume in the final mixture. This system has certain deficiencies since shutting off the air inlet to the pump may produce coasting, thereby dispensing additional material. Also, measurement in quantities less than multiples of complete strokes is not possible with limit switches, and if a double-acting pump is used, a different volume of material is dispensed on the upstroke as compared to that dispensed on the downstroke.